A large and growing population of users is enjoying entertainment through the consumption of digital media items, such as music, movies, images, electronic books, and so on. The users employ various electronic devices to consume such media items. Among these electronic devices (referred to herein as user devices) are electronic book readers, cellular telephones, personal digital assistants (PDAs), portable media players, tablet computers, netbooks, laptops, and the like. These electronic devices wirelessly communicate with a communications infrastructure to enable the consumption of the digital media items. In order to wirelessly communicate with other devices, these electronic devices include one or more antennas. Various types of antennas can be used in user devices.
A planar antenna is a type of radio antenna with a low profile, which can be mounted on a flat surface. A planar antenna includes a flat rectangular sheet or “patch” of metal, mounted over a larger sheet of metal called a ground plane. Planar antennas are simple to fabricate and may take a wide variety of forms. Typical planar antennas have two metal sheets that together form a resonant piece of transmission line with a length. The radiation mechanism arises from discontinuities at each truncated edge of the planar antenna.